Nope sorry, Ive got the wrong end of the stick (or the wrong end of the wheel to be more exact )

The washers youre after are for going on the reverse threaded screw that screws into the drill shaft yeah?
If so, I think my washers are about 10-12mm outer diameter with the hole for the reverse screw (cant remember the diameter off-hand) but I think youll probably need ones with a bigger outer diameter (maybe about 25mm?) to spread the load more